haven't received the upper yet, but was wondering if there are any compatibility issues such as the size of the pin-holes on the upper vs. lower (as I have heard is the case between bushmaster and colt)--  any info it greatly appreciated... thanks
v/r
will seabrook

99.9% positive you aren't going to have any problems.  I've got a CMT upper mated to a BM lower and no problems whatsoever.

thats good news--- thank you very much

v/r
will seabrook

The pin issue is strictly a COLT problem, as they are the one's who decided to produce rifles utilizing a different pivot pin size for some of their rifles.

Mating issue of these uppers or lowers could require special aftermarket pins designed to hold a standard pin size upper or lower to the oddballed Colts.

This issue is documented very well here at: www.biggerhammer.net, look in the upper section there for pics and pin sizes......

Mike

No problems with my BM lower and CMT upper.

I have done 4 builds with stripped Bushy lowers and CMT uppers. No problems. Good fit.

viator

NP here at all either, BM is a little deeper black but thats it.

You said it is a little deeper black, Is it very noticable?  

Brian

Quoted: You said it is a little deeper black, Is it very noticable?   Brian

Depends on how ticky you are. If you're a perfection freak, you probably shouldn't be an AR owner in the first place; since factory new complete rifles often show a slight color difference between upper and lower.

On the other hand, if you're like most of us, you'll put a light coat of lube on the two pieces, and not notice any difference except maybe when you're outside in strong sunlight.

I had a RR lower that was pretty tight with some of my BM uppers,some of them needed a couple of file strokes on some of the internal stuff to fit.
If you don't try to mix colt stuff with anything else (it can be done but is too much hassle in my op) you will likely never run into any problem and almost certainly never anything that can't be simply dealt with.
You do realise that CMT is the actual factory that makes many of the forgeings for the big AR companies?
I am not sure who does the final machine work (drilling holes and cutting slots ect) and who does the finish
of the parts but CMT is supposed to be the origin of lots of goodies .